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Water-electrolysis intends a favorable green technology to hold the worldwide energy and ecological disaster, but its efficacy is significantly restricted by the slow reaction kinetics of both the anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction (HER). Herein, the fabrication of multi-cation incorporated Fe2+/3+/Co2+ species into selenides nanorods (Fe@Co/Se 2 -NRs) and corresponding analysis of their catalytic activity for electrochemical (EC) and solar-driven water splitting as a purpose of the composition are reported. This efficient approach can fabulously endow electronic structure modulation and the direct evidence of electron-transfer-route between transition-metals and selenides, which are vital to improving the electrocatalytic activity, has never been confirmed before. For the first time, we explored the electron-transfer route of intensely-coupled Fe@Co/Se 2 -NRs catalyst, in which the Fe2+/3+/Co2+ species strongly-coupled to selenide through the Fe-coordinated Co-bridged-bond. Finally, density functional theory calculations disclose that the multi-cation doping effects into selenides are vital for enhanced electrocatalytic performance. [Display omitted] • The self-templated approach developed for bifunctional OER/HER electrocatalysts. • Iron-Cation-Coordinated Cobalt-Bridged-Selenides Nanorods structure increases the number of active sites. • The Fe@Co/Se 2 -nanorods reveal superior bifunctional OER/HER performance. • Requires only 1.5 V@10 mA cm−2 for electrochemical and solar-to-hydrogen conversion efficacy of ∼ 7.0% for water splitting. • DFT and XAS analysis exposed the electron-transfer route of intensely coupled Fe@Co/Se 2 -NRs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe-single atom anchored on carbon nanotubes catalyst was fabricated. • The catalyst exhibits excellent ORR catalytic activity in alkaline and acidic media. • The activity is boosted by the decorated Fe-N 4 on carbon nanotubes. Developing cost-effective and high-performance non-precious electrocatalysts for ORR in acidic and alkaline media is an urgent need for clean energy generation. A significant improvement in the ORR performance has been realized by the single-atom catalysts (SACs). However, activity deterioration caused by the dissolution of catalyst structure is still a lingering challenge. Herein, we report a simple strategy for protecting the structure of SAC by implanting/decorating Fe-ZIF-derived carbon nanotubes with Fe-N 4 , denoted as FeSA@CNTs. The as-developed FeSA@CNTs catalyst exhibits an outstanding ORR activity in an alkaline medium with onset potential (E o) = 0.998 V and half-wave potential E 1/2 = 0.898 V, which are 28 mV and 29 mV higher than commercial 20% Pt/C, respectively. Moreover, FeSA@CNTs in an acidic medium show an impressive high half-wave potential (E 1/2 = 0.8290 V) comparable to Pt/C (E 1/2 = 0.8292 V) which is better than most recently reported ORR catalysts. The density functional theory (DFT) validates that the smaller difference in the energy orbitals of Fe in Fe-N 4 and O 2 improved the electron transfer onto the reaction intermediate (OH*) in the rate-determining step, which provides the higher catalytic activity for FeSA@CNTs' in both acidic and alkaline media. [ABSTRACT FROM AUTHOR]